<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Math</title>
    <style>

    </style>
</head>
<body>

</body>
<script>
    //1.ceil(x)向上取整
    //2.floor(x)向下取整
    //3.round(x)四舍五入
    //4.random()取随机数【0.0-1.0】(含头不含尾)
</script>
</html>